Preserved arachnoid membrane acts as a predictor of postoperative visual improvement in clinoidal meningioma

OBJECTIVES

Improvement of patient visual outcome is very important in the treatment of clinoidal meningioma (CLM). The purpose of this study is to determine the association between arachnoid preservation and visual outcome.

PATIENTS

Fifteen patients with CLMs that caused visual impairment underwent surgery in our hospital. The patients included 4 men and 11 women, and the mean age was 53.3 years.

METHODS

The clinical findings of these patients were retrospectively reviewed. We divided the patients into two groups based on the presence or absence of the arachnoid membrane. Group 1 comprised cases in which arachnoid preservation was intraoperatively confirmed. Group 2 comprised cases in which the arachnoid membrane was not preserved. The Landolt C chart was used to evaluate visual acuity, and dynamic visual field tests using Goldmann perimetry were used to evaluate the visual field. Results were compared before and after surgery.

RESULTS

The visual acuity of the ipsilateral eye was significantly improved in Group 1 (p = 0.038). There were no other significant differences between the two groups in terms of tumor volume, patient age, and symptom duration.

CONCLUSIONS

Patients in which arachnoid preservation could be intraoperatively confirmed had good improvement in visual acuity. Further research with an increased number of cases is needed to confirm these findings.

Oligodendroglioma presenting with intradural spinal metastases: an unusual cause of cauda equina syndrome

We report a 37-year-old man with a primary intracranial oligodendroglioma presenting later with symptomatic multiple cerebrospinal fluid (CSF) intradural drop spinal metastases. This patient initially presented in 2006 with complex partial seizures. Initial histology demonstrated World Health Organization (WHO) grade 2 oligodendroglioma. The patient had further generalised seizures 7 months after initial tumour resection. MRI at that time confirmed tumour recurrence. The patient underwent a repeat craniotomy. Histology showed anaplastic transformation to a WHO grade 3 oligodendroglioma. About 30 months after his initial presentation, the patient developed a focal neurological deficit in the left leg with associated retention of urine. MRI of the neuraxis demonstrated widespread leptomeningeal metastatic drop deposits within the spinal canal. We discuss the mechanisms involved in tumour dissemination throughout the CSF. We also review the relevant literature regarding this phenomenon.

High-pressure hydrocephalus: A novel analytical modeling approach

Hydrocephalus is an abnormal accumulation of cerebrospinal fluid (CSF) within ventricles and subarachnoid space (SAS) as a result of disturbances in secretion or absorption procedures. It is believed that arachnoid villi cells, which are microscopic projections of pia-arachnoid mater that extend into venous channels in sagittal sinus, are the main sites for CSF absorption, but it is tempting to speculate that a significant portion of CSF is removed from the SAS by nasal lymphatic vessels around olfactory nerve. Thus, in this paper, we propose an analytical model of CSF-lymphatic-blood circulation, in which these two output pathways for CSF absorption have been considered. Mathematical relations governing the pressures in different interacting compartments of the brain are considered. In addition, for increasing the similarity of our model to the physiological conditions, the bulk flow mechanism, which is supposed to occur during CSF absorption, has been considered in our model. We used our model to simulate hydrocephalus. The results indicate that the lymphatic disorders have more considerable effect in decreasing CSF absorption, compared to the disturbances in arachnoid villi cells. Based on our modeling, we believe that disorders in lymphatic pathway may be a cause of high-pressure hydrocephalus. Surely experimental studies are required to validate our hypothesis.

Atypical growth pattern of a meningioma in an adult

A 49-year-old woman presented with a rare atypical growth pattern of meningioma without evidence of dural attachment manifesting as chronic headache associated with transient paresthesia and left motor disorders. On admission, neurological examination showed no abnormalities. Magnetic resonance (MR) imaging revealed a right temporo-parieto-occipital lesion, which appeared to involve the subdural space and filling the cortical sulci. The lesion caused peritumoral white matter edema. The tumor appeared hypointense on T(1)-weighted and hyperintense on T(2)-weighted MR images, with homogeneous enhancement after contrast administration. A biopsy of the lesion was performed. Histological examination indicated that the lesion was a meningioma. Intraparenchymal meningiomas should be considered in the differential diagnosis of intraaxial lesions in patients of any age.

Dissapearance of arachnoid cyst after rupturing into subdural space

Arachnoid cysts are developmental anomalies usually diagnosed in childhood. The most important complications of arachnoid cysts are subdural haematomas and hygromas and intracystic haemorrhage. In our case we present a 7-year-old boy whose arachnoid cyst ruptured into the subdural space following a mild head injury and disappeared after draining the subdural haematoma by burr-holes.

Arachnoid cyst mimicking normal pressure hydrocephalus. A case report and review of the literature

A case of a 61-year-old female patient who presents with the clinical triad of normal pressure hydrocephalus (NPH), abnormal gait, urinary incontinence and dementia. On CT scanning, she is found to have a large arachnoid cyst which mimicked the syndrome of NPH. This is also the 60th published case of arachnoid cyst presenting over the age of 60.

Arachnoid cysts in adults: long-term follow-up of patients treated with internal shunts to the subdural compartment

BACKGROUND

We have previously presented an alternative method for surgical decompression of intracranial arachnoid cysts. This minimally invasive method, with insertion of an internal shunt from the cyst to the subdural compartment, seemed to be an efficient and simple, and hence promising technique. The aim of the present study was to investigate the long-term results of this procedure.

METHODS

This study is a questionnaire-based retrospective study that includes 31 adult patients (>18 years) who were operated on in our department for an arachnoid cyst in the temporal fossa or overlying the frontal convexity with the internal shunt technique between April 1990 and October 2003. Follow-up ranged from 15 months to 14.8 years (mean = 8.2 years).

RESULTS

Of the patients, 83% were asymptomatic or had insignificant complaints at follow-up. A total of 17% reported no reduction of the preoperative complaints. No patient experienced worsening of the symptoms. The cyst was no longer visible on postoperative radiologic examinations in 37% of the patients. In 37%, the postoperative fluid volume was less than 50% of the original volume. In 13%, the cyst volume was reduced but the postoperative volume was greater than 50% of the original cyst volume. Thus, the cyst was unchanged in only 13% of the patients. There was no correlation between volume reduction and clinical improvement. A complication (subdural hygroma or hematoma) occurred in 7 patients, all with temporal cysts, leading to reoperation in 4. None of the complications caused permanent neurologic deficits or invalidity. Seven patients were reoperated on because of suspected or established treatment failure.

CONCLUSIONS

The internal shunt technique is a relatively simple, safe, and efficient alternative method for treatment of arachnoid cysts. It should be considered a valuable alternative in the treatment of arachnoid cysts.

Variations of disseminated choroid plexus papilloma: 2 case reports and a review of the literature

BACKGROUND

Choroid plexus papillomas are typically considered benign lesions, but histology is not always predictive of their behavior. These tumors can metastasize anywhere along the neuraxis and may be intraventricular, subarachnoid, or intraparenchymal. We present 2 cases that illustrate the wide diversity with which choroid plexus papillomas can disseminate.

CASE DESCRIPTIONS

The patient described in case 1 had a primary fourth ventricular choroid plexus papilloma that produced diffuse cystic subarachnoid and leptomeningeal lesions. Patient 2 also had a primary fourth ventricular tumor but with subsequent suprasellar and spinal drop metastases. Patient 1 was treated with temozolomide, resulting in regression of symptoms including headache and dizziness. Patient 2 has been treated with several modalities, including radiation therapy and chemotherapy, with slowing of symptom progression.

CONCLUSIONS

Variations of choroid plexus papilloma dissemination include intraventricular, subarachnoid, and leptomeningeal nodules or cystic lesions, and intraparenchymal locations. There is no consensus on the most effective treatment for choroid plexus papilloma metastases; surgical resection, chemotherapy, and radiation therapy may all yield benefits. The prognosis for patients with disseminated choroid plexus papilloma can range from prolonged stable disease and symptoms to death within months.

Surgical treatment of trigeminal neuralgia without vascular compression: 20 years of experience

BACKGROUND

There are few reports on the outcome of surgical treatment of TGN without vascular compression.

METHODS

Between 1984 and 2004, 668 patients underwent MVD for TGN. In 21 patients (3.1%), vascular compression was absent. The surgical strategy in these cases involved the following: (1) dissection and exposure of the entire trigeminal nerve root; (2) slight neurapraxia with bipolar tips at the trigeminal nerve root; and (3) isolation of trigeminal nerve with Teflon sponge fragments.

RESULTS

The patients' (female/male, 20:1) ages ranged from 33 to 77 years. Their right side was the most frequently involved (61.9%). Their mean duration of pain before treatment was 7.6 years (range = 1-20 years). At surgical exploration, vascular compression or anatomical abnormalities were absent in 15 patients (71.4%), arachnoidal thickening was present in 5 (23.8%), and fiber dissociation of the trigeminal nerve was present in 1 (4.8%). Mean follow-up after surgery was 17.7 months (range = 4-65 months). Immediate relief from pain occurred in all 21 patients. On Kaplan-Meier analysis, recurrence was maintained at 14.8% for 12, 24, and 36 months, increasing to 43.2% at 48 months. Permanent hypoesthesia was present in 6 patients (28.6%), whereas loss of corneal reflex was observed transiently in 1 (4.8%). Motor function of the trigeminal nerve was intact in all patients. No other complication was found.

CONCLUSION

The proposed surgical plan of standard MVD plus slight trigeminal nerve root neurapraxia is a safe and effective management option for TGN without vascular compression.

Effect of arachnoid plasty using fibrin glue membrane after clipping of ruptured aneurysm on the occurrence of complications and outcome in the elderly patients

BACKGROUND

In elderly patients with aneurysmal subarachnoid hemorrhage (SAH), complications including vasosopasm, subdural effusion, and late hydrocephalus, are liable to occur even after aneurysmal surgery. We examined prospectively the efficacy of arachnoid plasty using fibrin glue membrane during surgery of ruptured aneurysms in the elderly patients for preventing complications. The effects on the modified Rankin scale (mRS) and the Glasgow outcome scale (GOS) 3 months after SAH were noted.

METHODS

Total of 31 patients aged more than 70 years selected from a consecutive series of patients with aneurysmal SAH, were divided into two groups alternately, a group with arachnoid plasty (n = 16) and a control group without arachnoid plasty (n = 15). Statistical analyses were performed to assess relationships among various clinical and neuroradiological variables, especially between arachnoid plasty and occurrence of symptomatic vasospasm, subdural effusion, late hydrocephalus, or outcome such as mRS and GOS 3 months after onset.

FINDINGS

Statistical analyses revealed that arachnoid plasty were associated with late hydrocephalus and subdural effusion negatively, but with better mRS at 3 months after SAH. A tendency to be associated with less frequent symptomatic vasospasm was also noted.

CONCLUSION

Arachnoid plasty using fibrin glue is suggested to be effective in preventing complications associated with SAH and aneurysmal surgery. A better outcome in the elderly patients can be achieved.

Non-traumatic intradiploic arachnoid cyst

In this report, we present a case of non-traumatic intradiploic arachnoid cyst in a 65 year-old woman with a slow growing swelling in the right frontotemporal region without a history of head trauma, which was diagnosed intra-operatively. Extradural intracranial location of non-traumatic arachnoid cyst is a rare clinical entity with a few reported cases in the literature. Characteristic features of non-traumatic intradiploic arachnoid cysts are also described in this mini-review article.

Spinal leptomeningeal metastases from prostate cancer

OBJECTIVE

Prostate cancer is a well known cause of spinal column metastases; however, an intradural location is extremely rare. It is considered to be a type of leptomeningeal spread. Cerebral seeding has usually occurred by the time of presentation. Due to a poor prognosis, surgery is rarely indicated, and controversially discussed.

PATIENT AND RESULTS

We review the known cases of spinal leptomeningeal prostate cancer spread, including our patient, who developed paraparesis over 6 weeks, 3 years after prostate cancer was diagnosed. Following surgical decompression and resection, the patient additionally received radiation therapy of the spinal meninges and antihormonal treatment. 6 months after surgery, the patient is still ambulatory with a good quality of life.

CONCLUSION

Spinal leptomeningeal metastases occur at a late stage of systemic disease, and the prognosis is generally poor. In the literature, outcomes after surgery are reported as devastating, with mortality and morbidity rates of up to 20% and 60%. The aim of surgery is to relieve pain, preserve or even restore neurological function, and reveal histology if uncertain. This may be achieved by debulking the tumor without placing the patient at an unacceptably high risk. Surgery should be performed in selected cases of spinal leptomeningeal metastases, in patients who are still ambulatory with controlled systemic disease, and should be followed by adjuvant therapy.

Neuroradiologic and clinicopathologic features of oculoleptomeningeal type amyloidosis

OBJECTIVE

To clarify the pathogenesis of leptomeningeal amyloidosis in familial amyloidotic polyneuropathy amyloidogenic transthyretin Y114C (FAP ATTR Y114C).

METHODS

The authors analyzed eight FAP ATTR Y114C patients. Six patients showed CNS symptoms associated with leptomeningeal amyloidosis. To examine the function of the blood-CSF barrier and blood-brain barrier (BBB), the authors performed CSF and MRI studies. The authors also performed a histopathologic study of autopsy specimens to examine the distribution of amyloid deposition in the CNS.

RESULTS

CSF study showed high total protein concentrations and increased albumin CSF/serum concentration quotients (Qalb; an indication of blood-CSF barrier function). MRI with gadolinium (Gd) revealed enhancement from brainstem to spinal cord. Serial brain MRI studies with FLAIR images after Gd administration showed Gd leakage into the subarachnoid space (two patients). These findings suggested the blood-CSF barrier and BBB dysfunctions. Constructive interference in steady state (CISS) three-dimensional Fourier transformation (CISS-3DFT) sequence analysis demonstrated amyloid-induced funiculus structures joining the spinal cord and dura mater (one patient). Histopathologic study revealed intense amyloid deposition in leptomeninges, vessel walls, and parenchyma in spinal cord and the brain. These distributions of amyloid deposition are unique compared to other TTR related leptomeningeal amyloidosis.

CONCLUSIONS

Patients with familial amyloidotic polyneuropathy amyloidogenic transthyretin Y114C had CNS disorders related to amyloid deposition in leptomeninges, vessel walls, and parenchyma in spinal cord and the brain. The pathogenesis of CNS disorders may reflect disruption of the blood-CSF barrier and blood-brain barrier by amyloid deposition.

Extradural spinal arachnoid cysts associated with spina bifida occulta

INTRODUCTION

Spinal extradural arachnoid cysts are an uncommon cause of neural compression in children. Even more uncommon is the association of such cysts with spina bifida occulta.

MATERIAL

Two girls, 12 and 8-years-old, presented with left leg pain, deteriorating gait, clinical signs of left L5 and S1 root compression, without bladder or bowel symptoms. The first patient had left foot drop. The second patient had muscle wasting and smaller left foot with pes cavus. Radiographs showed spina bifida occulta of S1 in both. MRI revealed an extradural cyst at the S1 level, indenting the thecal sac and the L5 and S1 roots. At operation in both patients a large arachnoid cyst arising from a small dural defect in the axilla of the left S1 root was compressing and displacing it and the dural sac. It was removed and the defect was repaired. The first patient improved with complete recovery of the foot drop. An MRI at 12 months showed no cyst recurrence. The second patient made good recovery initially, but at 10 months developed recurrent symptoms. An MRI scan showed recurrence of the cyst with root compression. On repeat exploration a different dural defect was identified in a more anterior position and was repaired.

DISCUSSION

The coexistence of extradural arachnoid cyst and corresponding bifid spinal segment has not been described previously. It raises the suspicion that the dural defect giving rise to the arachnoid cyst may be due to segmental dural dysgenesis in the context of the dysrhaphic neuroectodermal malformation.

Serum and CSF vitamin A concentrations in idiopathic intracranial hypertension

BACKGROUND

Elevated serum retinol, CSF retinol, and serum retinol binding protein (RBP) levels have been found in some patients with idiopathic intracranial hypertension (IIH), but serum and CSF retinol levels have not been studied in matched serum and CSF samples in patients with IIH.

OBJECTIVE

To determine whether serum and CSF vitamin A concentrations are associated with IIH.

METHODS

The serum and CSF retinol concentrations were prospectively assessed in 20 patients with IIH and 20 control subjects.

RESULTS

CSF retinol concentration was higher in the patient group (median 575.91 nM) vs the control group (median 63.35 nM) (p < 0.05). There was no difference in serum retinol levels between control subjects (median 896.51 nM) and patients (median 1,002.62 nM) (p = 0.10). There was an association between higher vitamin A levels (> 250 nM) and IIH (p = 0.039). There was a correlation between CSF and serum retinol levels in patients (r = 0.82) and control subjects (r = 0.66).

CONCLUSION

Elevated CSF retinol concentration is associated with idiopathic intracranial hypertension (IIH), but serum retinol level is not associated with IIH.

Traumatic epidural haematomas of nonarterial origin: analysis of 30 consecutive cases

BACKGROUND

The purpose was to analyse the clinical and radiological findings, and management approaches used in 30 consecutive cases of traumatic epidural haematoma of nonarterial origin treated at one centre.

METHOD

Medical records for 30 patients surgically treated for epidural haematoma of nonarterial origin between 1997 and 2003 were reviewed. Epidural haematoma of nonarterial origin was diagnosed based on computed tomography (CT) and the bleeding source was confirmed intra-operatively. Admission status, outcome, fracture location, haematoma location/size/volume, and additional intracranial pathology were among the data noted. Two groups were formed for analysis: venous sinus bleeding (group 1) and other venous sources (group 2).

FINDINGS

The 30 cases accounted for 25% of the total number of traumatic epidural haematomas (n = 120) treated during the same period. The epidural haematomas of nonarterial origin locations were transverse sigmoid sinus (n = 11; 36.7%), superior sagittal sinus (n = 6; 20%), venous lakes (n = 5; 16.6%), diploë (n = 5; 0.16%), arachnoid granulations (n = 2; 6.7%), petrosal sinus (n = 1; 3.3%). There were 12 postoperative complications in 9 patients: recurrence (n = 4; 13.3% of the 30 total), pneumonia (n = 4; 13.3%), meningitis (n = 2; 6.7%), hydrocephalus (n = 1; 3.3%) and subdural effusion (n = 1; 3.3%). All recurrence cases were re-explored. Six (20%) patients died. Glasgow Outcome Scale (GOS) scores (mean follow-up 13.3 +/- 7.8 months) revealed 22 (73.3%) patients with favourable results (GOS 4-5) and 8 (26.7%) had poor results (GOS 1-3).

CONCLUSIONS

Cases of epidural haematoma of nonarterial origin differ from the more common arterial-origin epidural haematomas with respect to lesion location, surgical planning, postoperative complications, and outcome. Epidural haematoma of nonarterial origin should be suspected if preoperative CT shows a haematoma overlying a dural venous sinus or in the posterior fossa and convexity. The sinus-origin group had a high frequency of fractures which crossed the sinuses, and this might be diagnostically and surgically useful in such cases.

Endoscopic management of intracranial cysts

Object

Endoscopic fenestration has been recognized as an accepted treatment choice for patients with symptomatic arachnoid cysts. The success of this procedure, however, is greatly influenced by individual cyst anatomy and location as well as the endoscopic technique used. This review was conducted to assess what variables influence the treatment success for different categories of arachnoid cysts.

Methods

Thirty-three consecutive patients who underwent endoscopic fenestration for treatment of an intracranial arachnoid cyst were identified from a prospective database. The surgical indications and techniques were reviewed, and surgical success rates and patient outcomes were assessed. Specific examples of each cyst category are included to illustrate the technical aspects of endoscopic cyst fenestration.

Endoscopic fenestration of arachnoid cysts was successful when judged by cyst decompression, and symptom resolution was noted in 32 (97%) of 33 cases. The one patient with short-term treatment failure underwent a successful repetition of the operation. There were no surgery-related morbidities or deaths.

Conclusions

Arachnoid cysts are a relatively benign pathological entity that can be managed by performing endoscopically guided cyst wall fenestrations into the ventricular system or cerebrospinal fluid–containing cisterns. Proper patient selection, preoperative planning of endoscope trajectory, use of frameless navigation, and advances in endoscope lens technology and light intensity combine to make this a safe procedure with excellent outcomes.

CSF levels of angiogenesis-related proteins in patients with leptomeningeal metastases

The authors determined the levels of vascular endothelial growth factor (VEGF) and urokinase-type plasminogen activator (uPA) in the CSF of patients with leptomeningeal metastases (LM; n = 53), cancer patients without LM (n = 18), and subjects without malignancy (n = 25). Median levels of uPA and VEGF were significantly higher in patients with LM, supporting the hypothesis that angiogenesis contributes to LM. VEGF was negatively correlated with survival in patients with LM, suggesting its use as a prognostic factor.

Mechanisms of failure after endoscopic third ventriculostomy in young infants

OBJECT

The cause of failed endoscopic third vetriculostomy (ETV) surgery in the treatment of hydrocephalus may be a poor absorption of cerebrospinal fluid (CSF) or a new or continuing obstruction of CSF pathways. Particularly in infants, ETV failures often are ascribed to a still poorly developed CSF absorptive capacity.

METHODS

The authors report on a series of 11 infants younger than 1 year of age undergoing at least one repeated endoscopic surgery after a failed initial ETV for aqueductal stenosis. The following three patterns of endoscopic findings were observed: 1) reclosure of the ventriculostoma; 2) narrowing of the ventriculostoma; and 3) patent ventriculostoma with new arachnoid membranes in the basal cisterns below the floor of the third ventricle, not present at the time of the first ETV. In all patients, a new obstruction of CSF pathways was seen during repeated ETV or shunt surgery.

CONCLUSIONS

The authors' data strongly suggest that CSF pathway reclosure is the factor most responsible for ETV failure in obstructive hydrocephalus. According to both their experiences and to studies published in the literature, the formation of new arachnoid membranes or scars plays a far greater role in ETV failure than does poor CSF absorption, at least in aqueductal stenosis. It is hypothesized that infants have a higher tendency to form new arachnoid membranes than do older patients and that this factor may explain (at least in part) the higher ETV failure rate in patients younger than 1 year old.

Vascular smooth muscle actin is reduced in Alzheimer disease brain: a quantitative analysis

We analyzed smooth muscle actin (SMA) immunoreactivity in brain blood vessels of 10 ApoE 4,4 Alzheimer disease (AD) patients and 10 ApoE 3,3 AD patients matched for age, sex, and duration of dementia. We also examined 10 cognitively and neuropathologically normal controls matched for age and sex. Vascular SMA immunoreactivity in the arachnoid, grey matter, and white matter was quantified by image analysis. There was less SMA immunoreactivity in blood vessels of all AD patients when compared to cognitively and neuropathologically normal controls (p < 0.001). In addition, arachnoidal vessels of ApoE 4,4 AD patients had less SMA immunoreactivity than ApoE 3,3 AD patients (p < 0.05). There is decreased vascular SMA density in arachnoid, grey matter, and white matter blood vessels in patients with AD when compared to age matched, cognitively and neuropathologically normal controls. The severity of the loss of SMA within the AD group may depend on ApoE type.

Effect of craniocervical decompression on peak CSF velocities in symptomatic patients with Chiari I malformation

BACKGROUND AND PURPOSE

Peak CSF velocities detected in individual voxels in the subarachnoid space in patients with Chiari I malformations exceed those in similar locations in the subarachnoid space in healthy subjects. The purpose of this study was to test the hypothesis that the peak voxel velocities are decreased by craniocervical decompression.

METHODS

A consecutive series of patients with symptomatic Chiari I malformations was studied before and after craniocervical decompression with cardiac-gated, phase contrast MR imaging. Velocities were calculated for each voxel within the foramen magnum at 14 time points throughout the cardiac cycle. The greatest velocities measured in a voxel during the cephalad and caudad phases of CSF flow through the foramen magnum were tabulated for each patient before and after surgery. The differences in these velocities between the preoperative and postoperative studies were tested for statistical significance by using a single-tailed Student's t test of paired samples.

RESULTS

Eight patients with a Chiari I malformation, including four with a syrinx, were studied. Peak caudad velocity diminished after craniocervical decompression in six of the eight patients, and the average diminished significantly from 3.4 cm/s preoperatively to 2.4 cm/s postoperatively (P =.01). Peak cephalad velocity diminished in six of the eight cases. The average diminished from 6.9 cm/s preoperatively to 3.9 cm/s postoperatively, a change that nearly reached the significance level of.05 (P =.055).

CONCLUSION

Craniocervical decompression in patients with Chiari I malformations decreases peak CSF velocities in the foramen magnum. The study supports the hypothesis that successful treatment of the Chiari I malformation is associated with improvement in CSF flow patterns.

Cerebrospinal fluid volume depletion and its emerging clinical/imaging syndromes

Cerebrospinal fluid (CSF) volume depletion, due to CSF leakage or CSF shunt overdrainage, is typically indicated when patients present with orthostatic headaches, with or without several other symptoms: neck or interscapular pain, nausea, emesis, diplopia, changes in hearing, visual blurring, facial numbness or weakness, and radicular upper-limb symptoms. Cerebrospinal fluid pressures typically are quite low and head magnetic resonance images typically reveal diffuse pachymeningeal gadolinium enhancement, with or without evidence of sagging of the brain and less frequently with subdural fluid collections, enlarged cerebral venous sinuses or pituitary gland or decreased ventricular size. Magnetic resonance imaging has revolutionized detection of spontaneous CSF leaks, leading to identification of far more cases and recognition of several clinical/imaging forms of presentation of the disorder. These forms, which are different from the "typical" presentation, include a group with consistently normal CSF pressures (normal pressure), another group without abnormal meningeal enhancement (normal meninges), and a group without headache (acephalic). Each of these forms can be seen in a setting of documented and ongoing CSF volume depletion. Awareness of CSF volume depletion is increasing, and its clinical and imaging spectrum is broadening.

The inner membrane of chronic subdural hematomas: pathology and pathophysiology

There is no clear plane between the dura and arachnoid in situ. Instead of the virtual subdural space, there is a dura-arachnoid interface layer, which is structurally the weakest throughout the meninges. An extravasation of blood within the dural border layer splits it, leaving a few tiers of dural border cells over the arachnoid. These cells cover the internal surface of the hematoma, proliferate, and later on, form the inner membrane. The outer membrane is related to hematoma enlargement because of the repetitive hemorrhages whereas the inner membrane is related to liquefaction of the subdural hematoma. As the inner membrane plays a pivotal role in the pathophysiogenesis and determination of the location of chronic subdural hematoma, histologic, ultrastructural, and clinical analyses were performed with correlations to the dura-arachnoid interface and the so-called "subdural space."

The possible role of CSF hydrodynamic parameters following in management of SAH patients

It is suggested that reduced intracranial compliance may be present even when measured ICP is normal and may precede clinical deterioration. Our findings reflect a decompensation of hydrodynamic parameters more pronounced 4-7 postictal days, when compliance is reduced not only in patients with poor clinical condition, but also in patients with Hunt-Hess grade I-III. Increased CSF outflow resistance in the first few days is not surprising; it is thought to be due to the blockage of flow of CSF through the basal subarachnoid cisterns and clogging of the arachnoid villi with erythrocytes and fibrin. Enlargement of ventricles seen on CT scan at the same time suggests the development of acute hydrocephalus. During the first days after SAH, our data reflects evidence of ventricular enlargement in patients presenting with both poor and better clinical condition. We conclude that the monitoring of ICP and dynamic measuring of CSF hydrodynamic parameters is important for longer than the generally accepted few days for selected cases after SAH.

Endoscopic observation of a slit-valve mechanism in a suprasellar prepontine arachnoid cyst: case report

OBJECTIVE AND IMPORTANCE

There are several theories regarding the genesis of arachnoid cysts. However, controversy continues over what mechanisms are involved in the formation of the cysts.

CLINICAL PRESENTATION

A 6-year-old female patient presented with precocious puberty. The results of a neurological examination were unremarkable. Magnetic resonance imaging revealed a large suprasellar prepontine arachnoid cyst.

INTERVENTION

An endoscopic ventriculocystostomy via a right frontal burr hole was performed. During inspection of the cyst, we clearly observed a slit-valve mechanism that was obviously responsible for the formation and enlargement of the cyst. The valve was formed by an arachnoid membrane surrounding the basilar artery. Synchronous with pulsation, the valve opened and closed rapidly.

CONCLUSION

A slit-valve mechanism seems to be at least one factor of the genesis of suprasellar prepontine arachnoid cysts.

Accelerated myelination in early Sturge-Weber syndrome: MRI-SPECT correlations

The prognosis of Sturge-Weber syndrome (SWS) is partly related to early occurrence of seizures but the diagnosis of this phakomatosis may be difficult during the 1st year of life. We have performed a retrospective study of seven patients with confirmed SWS (age 7 days to 3 months). None of the patients was asymptomatic at the time of the study. They all underwent MRI (T1 and T2 sequences) and single photon emission computed tomography (SPECT) at the same time. Regional cerebral blood flow was measured using xenon-133. In all cases, myelination appeared to be accelerated in the areas underlying the leptomeningeal angioma on both MRI sequences. In five cases, SPECT showed hyperperfusion in the damaged hemisphere. In one case, the SPECT was symmetrical and in another it showed hypoperfusion in the damaged hemisphere which was already atrophied. These data suggest that the accelerated myelination is not related to ischemia but to transient hyperperfusion. This MRI pattern can be helpful for the early diagnosis of SWS, which is of utmost importance for preventive antiepileptic treatment.

Hydrocephalus: is impaired cerebrospinal fluid circulation only one problem involved?

Hydrocephalus is a complex disease of the brain as a whole, and imbalance between cerebrospinal fluid (CSF) formation and absorption is not the sole mechanism involved in its pathophysiology. In the absence of a lymphatic system in the central nervous system, open communication between CSF and interstitial fluid (ISF) of the brain may contribute to maintaining homeostasis of the brain, keeping the microchemical environment in good balance. Membranes or cell layers separating CSF from ISF of the brain do not provide impermeability, so the CSF communicates with ISF across the ependymal layer and the pial surface of the brain. In contradiction of the classical theory, the CSF one may obtain at the cisterna magna, for instance, is different from the newly formed CSF out of the choroid plexus, because it has been modified by the free communication between CSF and ISF spaces as the CSF descends along the neural axis. Free flow of water and some smaller molecules provides a bidirectional movement of water and other materials, and this must play an important role in brain volume control. The significance of this role should not be overlooked in regard to the pathophysiology of hydrocephalus.

Barrier functions of the leptomeninges: a study of normal meninges and meningiomas in tissue culture

The anatomical arrangement of the pia mater suggests that it may act as a regulatory interface between cerebrospinal fluid and the surface of the brain and between arterioles within the brain and the surrounding neural tissue. However, the functional aspects of such a barrier are difficult to evaluate in vivo. In the present study, the enzymic content and endocytotic capacities of normal leptomeningeal cells in situ and meningioma cells in confluent tissue culture are examined in relation to barrier functions of meningeal cells. Growth of cells in culture was obtained from human fetal and newborn rat leptomeninges and from 9/13 meningiomas. But, in only two meningiomas were the cultured cells characterized as meningeal in origin by using the strict criteria of desmosomes identified by immunocytochemistry or by electron microscopy. These two tumours had high (8-8.7%) Ki-67 labelling indices. Glutamine synthetase activity is present in normal meninges and in meningioma cells in culture; this enzyme together with catechol-O-methyltransferase could play a role in limiting the diffusion of neurotransmitters into brain tissue. A steady rate of endocytosis of carbon particles and fluorescent latex beads, 0.2-1 microns in diameter, was observed in cultured meningioma cells. Such endocytosis was inhibited by cytochalasin B indicating the active participation of intracellular microfilaments. Similar endocytosis has been observed in normal leptomeninges in vivo. The results of this study suggest that meningioma cells in culture reflect the barrier functions of the pia mater and may be used as a model to further investigate the functions of the pia mater.

Functional ultrastructure of cerebrospinal fluid drainage channels in human arachnoid villi

The functional ultrastructure of the human arachnoid villi was studied to clarify drainage channels of cerebrospinal fluid (CSF). The apical portion of each villus was usually covered by the arachnoid cell layer alone with no endothelial investment, whereas most of the stromal central core was further encompassed by a fibrous capsule with an endothelial investment. Accordingly, the CSF-blood interface was assumed to be in both the endothelial cells and the arachnoid cell layer. The former were characterized by abundant micropinocytotic vesicles and occasional intracytoplasmic vacuoles, whereas the latter was characterized by numerous extracellular cisterns measuring 10 micron in maximal diameter. There were no free communications such as endothelial open junctions or endothelium-lined tubules. In the villi affected by subarachnoid hemorrhage, endothelial cells were intact and continuous despite the erythrocyte-packed subendothelial space, which appeared to be on the verge of rupturing. Intracytoplasmic vacuoles, measuring less than 1 micron diameter, sometimes contained serum protein-like substance. Furthermore, the extracellular cisterns were distended by intact or disintegrating erythrocytes that served as a natural tracer, suggesting CSF drainage channels. It is conceivable that, in human arachnoid villi, the extracellular cisterns of the arachnoid cell layer contribute to the passive transport of CSF, whereas micropinocytosis and vacuolization mechanisms of the endothelial cells are available for active transport.

Cerebral vasospasm: a theoretical relationship between systolic thrust and pia-arachnoid fibers

It is postulated that the repetitive thrust of a sensitized blood vessel, at the peak of systole, against a taut pia-arachnoid fiber may produce or accentuate vasospasm.

Empty sella syndrome

Awareness of the entities of primary and secondary empty sella syndrome and the use of current CT scanning techniques should allow one to differentiate between these conditions and persistent or recurrent pituitary adenoma. This distinction is important to make so unwarranted surgery or radiation therapy will not be advised.

Pathogenesis of raised cerebrospinal fluid pressure

Raised cerebrospinal fluid pressure may be caused by (a) subarachnoid CSF circulation blocks (b) obstruction of CSF absorption in the arachnoid villi (c) disorders of the venous return from the superior sagittal sinus to the heart. The common factor in these mechanisms is obstructed CSF drainage. Some clinical conditions illustrating these principles are reviewed.

Pathogenesis of pseudotumor cerebri syndromes

Intracranial hypertension in the absence of an intracranial mass lesion or hydrocephalus can be caused by an alteration of one or more of the four determinants of cerebrospinal fluid (CSF) pressure: (1) intrasagittal sinus pressure, (2) resistance of arachnoid villi to the egress of CSF, (3) rate of production of CSF, and (4) compliance of the CSF space. The pseudotumor cerebri syndrome of obese young women may be caused partially by increased CSF production. Estrone (produced by the conversion of androstenedione by adipocytes) probably induces the menstrual irregularities of these women and may affect CSF secretion. Pseudotumor cerebri syndromes associated with other conditions may be separated into pathogenic categories.

Agenesis of arachnoid granulations and its relationship to communicating hydrocephalus

The authors discuss reabsorption of cerebrospinal fluid in relation to the post-mortem findings in two children, one with total agenesis of the Pacchionian system accompanied by hydrocephalus, and the other with a subtotal agenesis and no hydrocephalus. Case 1 is the only known documented case of total agenesis of the Pacchionian system and gives credence to the idea that an impaired reabsorption of cerebrospinal fluid at the level of the Pacchionian system is a cause of hydrocephalus. The patient in Case 2 showed only two small areas of arachnoid granulations containing a few flattened, microscopic villi of normal cellularity.

The role of mechanical factors in the pathogenesis of short-term and prolonged spasm of the cerebral arteries

✓ The authors describe fibrous structures they name “chordae” that stabilize the position of arteries in cerebral subarachnoid spaces. The innervation of these structures and their relation to the innervation apparatus of the arterial wall is discussed. Animal experiments and human autopsy material were used to study the role of the stabilizing structures in the pathogenesis of arterial spasm following the rupture of saccular aneurysms. Mechanical stimuli produced short-term but not prolonged arterial spasm.